Comparative assessment of bioactive compounds, antioxidant capacity and nutritional quality of red seaweeds and water spinach

Abstract

Each food form is considered to have greater affinity if enriched with nutritional and bioactive compounds. This study was undertaken to evaluate the bioactive compounds, antioxidant properties, and proximate composition of two seaweeds i.e., Hypnea musciformis and Gelidium pusillum and a freshwater weed i.e., Ipomoea aquatica, in search of potential plant food sources with greater medicinal values. Bioactive compounds, e.g., total phenolic content (TPC), carotenoid, total flavonoids, ascorbic acid, tannin, and antioxidant activity by means of total antioxidant content (TAC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, and Ferric reducing antioxidant power (FRAP) were measured. The proximate compositions (e.g., protein, carbohydrate, etc.) of these study samples were also determined. Ipomoea exhibited 36.19% less antioxidant activity than seaweed samples (ranging from 19 to 22 mg AAE/g). The samples TPC (mg GAE/g) followed the order Gelidium (48.37 ± 0.96) > Hypnea (11.37 ± 0.92) > Ipomoea (9.4 ± 0.36). The DPPH radical scavenging activity of I. aquatica was 4 times less than the seaweed. Nevertheless, freshwater weed’s total carotenoids content was one and a half times higher than seaweed samples. The amount of ascorbic acid, tannin, and FRAP were also found higher in seaweeds. However, flavonoid content was higher (8.09 ± 1.4 mg QE/g) in freshwater weed. However, proximate compositions were about 1.5 times higher in seaweed. The non-parametric statistical analysis showed a significant difference between Hypnea versus Ipomoea and Gelidium versus Ipomoea (α=0.05; p<0.05) in each of the antioxidant and bioactive compound parameters. The study results suggested that red seaweeds are verily more compatible in contrast with freshwater weed for most of the parameters and could be used as a prospective source of human diets.